The present invention relates to rotary filtering apparatus and more particularly to a disc filter and disc filter sectors.
Disc filters are used in the pulp and paper making industry for many purposes. For example, one existing disc filter is designed for processing paper machine white water into high quality filtrate while, at the same time, recovering the fibers. It is also designed for thickening low to medium freeness pulp, especially where high discharge consistency is required. A portion of one such disc filter is illustrated in FIG. 1.
Each disc is built up by typically 3 to 30 open-grid sectors connected to corresponding filtrate channels in the shaft, with space between each sector to allow for the pickup and discharge of thickened pulp. The open-grid sector design helps to eliminate the risk of pulp and debris accumulating inside the sector. This design also allows the fabric to be cleaned from both the outside and inside by a spray water jet passing through the open sector. This keeps the cloth cleaned longer, which improves effectiveness.
To minimize the time needed for cloth exchange during preventive maintenance, the disc filter includes a cassette concept that makes it possible to dismount and mount sectors quickly. The sectors are accessible from a platform through hood doors. As illustrated in FIG. 1, a web of radial arms receives and supports each individual sector, and connects the sectors together in a watertight fashion.
The disc filter is designed for both clockwise and counter-clockwise rotation. An oscillating nozzle cleans the filter cloth before the filtration procedure begins again.
Current sector design is relatively costly to manufacture, both from a material and an assembly standpoint. It would be advantageous to reduce both the amount of material and the amount of assembly time needed for the manufacture and repair of such disc sectors.